Hydrocarbon alkylation process



June 26, 1945. M. P. MATuszAK HYDROCARBON ALKYLATION PROCESS Filed oct.5, 1942 2 sheets-sheet 1 June 26, 1945. M p MATUSZAK 2,379,368

HYDROCARBON ALKYLATION PROCESS Filed Oct. 5, 1942 v2, Sheets-Sheet 2 M.MATUSZAK' BY ATI' NE f Patented June 26, 1945 nYDRocAnBoN ALxYLA'rroNPnoonss Maryan P. Matuszak, Bartlesville, Okla., assigner to PhillipsPetroleum Company, a corporation of Delaware Application October 5,1942, Serial No. 460,843

2 Claims.

This invention relates to improvements in mixing iluids, moreparticularly to improved method and apparatus for conducting chemicalprocesses involving adding continuously at least one fluid to a zonewherein it is rapidly mixed with the contents already present in thezone, and still more particularly to improvements in `conducting analkylation process involving introducing one or more :duid reactants toa reactionmixture under reaction conditions. It has both process andapparatus aspects.

In many processes, mixing of fluids is desirable or necessary. When theiluids are mutually chemically inert during the mixing, so that theproduct is merely a physical mixture or emulsion of the original fluidswithout these fluids being changed chemically, the precise manner ofbringing the iiuids together may be `relatively unimportant; that is,provided that the final proportions of the uids are within certainlimits, the nature and composition of the product may be relativelyindependent of such factors as the order of bringing the fluidstogether, the rate of mixing, and the like. When, however, the fluidsare mutually chemically reactive, and especially when one or more ofthem can undergo more than one chemical reaction, the precise manner ofmixing may be very important in determining the.

nature and composition of the product.

Although certain aspects of the present invention may be applied to themixing of any fluids A specic object of this invention isfto provideimproved means for mixing mutuallychemically reactive iluid reactantsunder reaction conditions (Cl. 26o-683.4)

Another specic object of this invention is to'v provide improved meansfor conducting the a1- kylation of an alkylatable hydrocarbon with anlalkylating agent or alkylant in a zone in which suitable conditions aremaintained for the alkylation in the, presence of a,l mobile alkylationcatalyst, whereby the alkylation is favored, and competitive reactionsare. minimized.

Another speciiic object of this invention is to provide improved meansfor the production of alkylated compounds.

Another specic object of this invention is to provide means for eiectingcooling of an alkylation reaction mixture while at the same timerecovering in puriiied condition at least part of a volatile alkylationcatalyst contained in the al'- kylation reaction mixture.

Other objects and advantages of this invention will be apparent to`those skilled in the art from the' following description, theaccompanying drawings, and the appended claims.

In one specific embodiment, this invention comprises means whereby atleast one of two or more fluids is introduced into a mixing zone throughone or more openings that are in continuous motion with respect to themobile contents of the zone, the openings being preferably so locatedinmoving devices for imparting vigorous turbulent and/or circulatorymotion to the contents of the zone thatl relative movement of thecontents of the zone past the openings occurs at relatively highvelocity. Examples of such moving devices are impellers, propellers,other mechanical agitators of various types, and the like. If desired, apart oi the total fluid being introduced into the mixing zone may beintroduced through openings in selected stationary spots at whichmovement i of the contents of the zone past the openings occurs atrelatively high velocity; such openings may be in, for example, guidingand/or turbulence-aiding partitions, 'ns, bailies, other protuberancesof various types, and the like. For

' mixture.

in such manner that the relative concentration of a'selected reactant isminimal..

Another specific objectA o1' this invention is to provide improved meansfor rapidly dispersing a iirst liquid reactant in a reaction zonecontaining a second liquid reactant, whereby a desired reaction betweenthe two reactants is favored, and one or more competitive reactionsconsuming the rst liquid reactant are minimized.

sof

removal of heat from the resultingmixture, evaporative cooling may bepracticed as hereinafter speciilcally detailed for a catalyticalkylation' Understanding oi this invention may be facili.- tated byreference tothe accompanying drawings, in which Fig. 1 is a schematicflow-diagram illustrating one specific arrangement of apparatuswherewitii certain aspects of the invention may be practiced, Fig. 2 isa diagrammtic section of For the sake of simplicity and by way ofexample.Flg. 1 is directed to a relatively simple process for catalyticalkylation of compounds. However, it will be understood that someaspects of the invention are quite vbroad and are not to be restrictedor limited to any particular application, except as specified in theappended claims, since these aspects may be advantageously applied tothe mixing of any selected mobile fluids whatsoever.

In the arrangement of Fig. 1, an alkylatable compound is introduced, asthrough inlet I i, into alkylator I3, wherein it is alkylated with analkylating agent or alkylant, introduced as through inlet I4, thealkylation being effected in the presence of an alkylation catalyst,introduced as through inlet I6.

The compound introduced through inlet i I may be any that is capable ofbeing alkylated with a suitable alkylating agent under the influence ofa mobile alkylation catalyst. In a broad sense, it may be practicallyany of many generally organic compounds comprising hydrogen, asalln'laftion may be considered to be the replacement of one or morehydrogen atoms by an equal number of alkyl groups. An exceedingly largenumber of speciilc replacements of this type, wherein the hydrogenreplaced is initially attached to carbon, or nitrogen, or oxygen, orsulfur, or some' other element, are possible. The rank-.cement may ofcourse be effective or virtual rather than actual, as for example in thealkylation of water with an oleiln to form an alcohol, in which theoleiln and a hydrogen of the alkylatable compound unite to form thealkyl group of the product. In this broad sense, alkylation includesmany reactionsl commonly known by more specific names, such as hydrationof oleilns, esterication of acids with alcohols, polymerization andcopolymerization of oleflns, alkylation of hydrocarbons, and variousother well-known juncture or condensation reactions. Solely for the sakeof simplicity of description and not by way of limiting the presentinvention, alkylation of hydrocarbons may be taken as being typical.

Hence, the compound introduced through inlet Il may be an alkylatablehydrocarbon, such as for example an aromatic hydrocarbon, exemplified bybenzenetoluene, etc., or an isoparamn, exempliiled by iso-butane,isopentane, etc., or a normal paratlin, exemplified by normal butane,normal pentane, etc., or the like. Such hydrocarbons naturally are notcomplete equivalents of each other, so that optimum conditions foralkylation of any particular hydrocarbon may not be through inlet I4may-be any compound that, by

chemical reaction with an alkylatable compound produces a product amolecule of which has an alkyl group in place ol' an original hydrogenatom: other products may or may not be simul-v taneously produced. Manyalkylating compounds are known; among them are olenns, dioleilns.cycloparamns, acetylene, alcohols, ethers, esters, alkyl halides, andthe like. Naturally, these allcylants are not complete equivalents ofeach other, since they vary widely in the ease with which theyparticipate in the alkylation reaction. Among olens, the ease ofparticipation in the alkylation reaction generally decreases withdecrease in the number of carbon atoms per molecule, so that ethylene,which is the lightest of the oleflns, is the least reactive. Amongcycloparafns, which are isomeric with olens, the decrease in the ease ofparticipation in alkylation with decrease in the number of carbon atomsper molecule is overbalanced by a decrease with approach to a six-carbonring, so that cyclohexane appears to be the least reactive of thelow-boiling cycloparailins, whereas cyclopropane and methylcyclopropaneappear to be the most reactive among them.

Among alkyl compounds, such as alcohols, ethers, halides, and the like,the ease of participation in the alkylation reaction decreases withdecrease not only in the number of carbon atoms in the alkyl group butalso in the branching at the pivotal carbon atom, so that isomeric alkylgroups decrease in reactivity from tertiary through secondary toprimary. In addition, the reactivity of the alkyl group is aifected bythe nature of the rest of the molecule and also by the reactionconditions, especially the nature of the catalyst, so that, for example,in the presence of hydrofluoric acid as catalyst, an alcohol is,

somewhat surprisingly, more reactive than the corresponding chloride.

For the sake of simplicity of the present description, a preferredalkylant may be taken to be an olefin, which has the advantages that ithas a high reactivity and that it does not producemetatheticalby-products, such as for example water, relatively volatilehydrogen halides, and the like.

The alkylation catalyst introduced through inlet I6 may be any mobilematerial capable of satisfactorily promoting the alkylation of thechosen alkylatable compound with the chosen alkylant. Many alkylationcatalysts are known; among them are materials comprising one or more ofthe following: hydroiluoric acid, boron iluoride, sulfuric acid,chlorosulfonic acid. fluorosulfonic acid, phosphoric acid, organiccomplexes or sludges or other materials comprising suitable catalytichalides, such as chlorides and bromides, of polyvalent metals of thetype of aluminum, boron, iron, zirconium, etc., and the like. Naturally,these alkylation catalysts are not complete equivalents of each other,since they vary greatly in their catalytic properties and consequentlyin their suitability for particular alkylation reactions and forparticular reaction conditions of temperature, contact time,concentrations, and the like.

For the sake of simplicity of description, the alkylation catalyst maybe taken to be a liquid,

' preferably such a liquid as concentrated hydroliuoric acid or sulfuricacid. Concentrated or substantially anhydrous hydroiiuoric acid has theimportant advantage of being usable throughout a wide temperaturerange', including elevated temperatures at which other catalysts exhibitdeleterious orA undesirable tendencies resulting in formation of tars,oxidation by-products, and/or the like, sometimes accompanied byexcessive consumption of the catalyst itself; it also ha; the advantageof having s relatively low specinc gravity, so that any tendency forstratification of the reaction mixture is relatively small. Because o fthese advantages, the present description may be further simplified bybeing devoted primarily to this catalyst, without, however, limiting the.invention to any particular catalyst or group of catalysts, except asspecified inthe appended claims.

Many different methods or procedures for bringing together the'alkylatable' hydrocarbon, the olefin, and the alkylation catalyst inalkylator I3 are possible, To be. most fully satisfactory, the methodpreferably should be such that the olefin andthe cataiystare not brought4together without a"'considerable molecular excess of the alkylatablehydrocarbon being also present; otherwise, polymerization and/or otherundesired reactions, instead of the'desired alkylation, may,

be encouraged. 'Hence preferably atleast the catalyst and the olefinshould enter the alkylator through separate or individual inlets. Theallcylatable hydrocarbon may enter similarly through a separate orindividualinlet, or'itmay be advantageously used, at least in part, todilute the lincoming olefin and/or to presaturate the incoming catalyst.In the ,arrangement of Fig. 1, addition of alkylatable hydrocarbon tothe olen and to the catalyst .may be conveniently made throughconduits!! and I9, in proportions controlled by valves and 2l,respectively.

At least part of the alkyla'table hydrocarbon is preferably introducedinto alkylator i3-in such or bushings. When the moving device comprisesat least one propeller, impeller, stirrer, or the like. denoted by 5, ona. shaft, such as sha-ft 23, that is driven or rotated mechanically, asby motor 24, the sweeping action may be'insured by surrounding vtheshaft by a concentric apron, such as apron 25, for an appreciabledistance. so that tle incoming hydrocarbon must pass between the shaftand the apron before it can enter into the'reaction zone. Y

In accordance with one aspect of the present improved mixing means, thealkylant is advantageously introducedv into the reaction mixture inalkylator `i3 through vshaft 2l, which is suitably provided with aninternal duct or ducts and with outlet openings in the rotatingpropeller, mpeller, or the like, represented in Fig. 1 by arrow heads26. The wiping or sliding action be-v tween the surface of the rotatingdevice and the reaction mixture, and the turbulence in the ref actionmixture caused by the rotating device, rapidly disintegrate and dispersethe material so introduced to such a high degree that a similar effectcould be obtained only by an infinite number of alkylant-introdu'ctionpoints scattered throughout the reaction zone.

No special arrangement for introducing the al- I aava'acs v vary widely,depending reactants and-the particular catalyst present.

' ture and in consequence ating agent preferentially from the reactionmix- 'Ihe reaction conditions in alkylator I3 may mostly on theparticular For example, the reaction time, by which is meant herein theaverage time of residence of l widely, especially when the reactants inthe alkylator, few seconds to several hours or temperature, it usuallymust be furie acid is the catalyst than when hydroiiuoric acid is thecatalyst. The temperature may vary hydrofluoric acid is the catalyst, asfrom subatmospheric temperatures to the critical temperature of thereaction mixture; but for sulfuric acid the upper'temperature usuallymust be limitedlto 4about 35 C., because of the strong oxidizingproperty of this acid.

may vary from a more. At a given The pressure'may be as high'as may bede sired, and advantage may be'taken of the fact I vthat high pressures.favor the alkylation reaction thermodynamically. Usually, however,pressures sufficient to maintain tle reaction mixture substantially linthe liquid phase are adequate, so that especially high pressures areordinarily'not necessary. In fact, the pressure may even be so low 'thatcertain lowboiling alkylants,.such as ethylene and/or propy1ene, may .beintroduced' into the reaction mixture as gases or vapors `and -.wouldexist `in'the gaseous phase in the'reaction 'zone were the alkylant notdissolved in the other components present. yThe" ratio of catalyst tohydrocarbons in the reaction zone should be 'high enough for easymaintenance of a large catalyst surface; a ratio of about 1:1 by `volumeis generally preferred; a ratio of from about 0.5:1 to about 5:1 .byvolume is usually satisfactory, but ratios outside of this range mayalso be useful in many particular cases.

The reaction conditionsfnaturally'are at least somewhat'interdependent,and the fixing of one ormore of them may necessitate that others beadjusted correspondingly, in order to obtain desirably satisfactoryresults. However, satisfactory conditionsfor anyparticular applicationwill be well'within the skill of those versed in the present-dayalkylation art. 4

Especially important among' the reaction conditions is theAmolecula-r'ratloof the alkylatable hydrocarbon to the alkylant.-

ratio, the more favored is the alkylation reaction, andthe less favoredaresuch sideereactions as polymerizationof the alkylant andchemicalreaction of the .alkylant with the'catalyst. That is, the concentrationof the alkylant should be minimal, and so far as possible thecomposition oi' the feed or feeds, Lthe'exa'ctimanner of feeding,

and the manner of dispersal fof the'feeds in thev alkylation zoneshouldbesuch as to ensure a minimal alkyiant 'concentration in the allryls-v vtion zone.v In thefover-'all feed there must always be `amolecularfexcess of' the alkylatable Although some alkylate is'formed ifthe alkyl- .atable hydrocarbonintroducedfinto alkylator kylationcatalyst into alkylator I3 has thus far been found worthy of mention,provided only that the introduction avoids the 'formation ofl arelatively stagnant pool of the "catalyst, since such a pool tends toextract the-olefin or other alkyl- 'll is molecularly only equal to.or`even less than, vthe olefin simultaneously introduced, this alkylate" isrelatively poor in both yield and `quality because a. considerablepartfof the olefin undergoes undesired reactions.l These`undesiredre kactionsinvolving the 'olefin are thermodynamito promoteconsumption of thealkylating agentby polymerization and/or other -undesiredside-reactions.

longer when sul-l The greater vthis v cally favored by increase in theolefin concentration, as is obvious from the following chemicalequations for two reactions representative of those occurring whenthe-olefin is butylene and the catalyst is hydrofluoric acid:

When an allavlatable hydrocarbon, such as for example isobutane, ispresent, the following typical desired allwlation reaction also occurs:

`At first glance it might appear from this 'equation that thisallrylation reaction should be also -favored by increase in the olenconcentration. lbut such a conclusion would be correct only -if It maybe noted, however, that the concentration of the alkylation product isperforce decreased when the concentration of the alkylatable hydrocarbonis increased beyond that molecularly the alkylatable hydrocarbon. 1

equivalent to the initially present olefin, so that i increasing theconcentration of the alkylatable hydrocarbon may be said to be doublyfavorable.

Conversely, decreasing the concentration of theA alkylating agent orolefin favors the alkylation reaction, provided of course that theconcentration is not decreased to the point of complete disappearance.

To decrease or minimize the olen concentration throughout the alkylationzone requires vigorous mixing or agitation and preferably also internalor external recirculation of the` alkylation mixture, so that theincoming olefin is quickly dispersed and is consumed in the desiredreaction without building up a local concentration that would favorproduction of undesired products. Advantageously, the dispersal of theolefin is enected by introducing it into the alkylation zone at pointsin the mixing and recirculating mechanism that come into contact withthe maximum amount of reaction mixture per unit time. Thus, when themixing and recirculating is being effected by a moving device, whichusually is most satisfactorily someform of rotary stirrer, impeller, orpropeller, the olefin preferably is introduced into the reaction mixturethrough one or more openings located at points in the moving device atwhich the linear velocity is at or near the maximum, for example at ornear points farthest removed from the-shaft of the rotary stirrer. Lesspreferably, the olefin'may be introduced at stationary points past whichthe reaction mixture flows at relatively high velocity, as in bailleplates or ilns designed to aid in agitating or comminuting the reactionmixture. By such means as these, local concentrations of the olenn insluggish regions of the reaction zone are avoided, and the concentrationof the olen throughout the reaction zone is' maintained at the desiredAfter a suitable average time of residence in alkylator I3, the reactionmixture or emulsion is passed therefrom into suitable separating and/orrecovery means wherein it is separated into the desired products,recycle fractions. and the like. For example, when the hydrocarbons andthe catalyst are relatively immiscible under the prevailing conditions,the reaction mixture may be passed directly through conduit 21 toseparator 2l, in which it is separated into a hydrocarbm phase and acatalyst phase, as by gravity and/or centrifugation.

Usually, however, and especially when hydroiiuoric acid is the catalyst,the hydrocarbons and the catalyst are at least partly miscible. Thedegree of miscibillty depends principally upon the particular materialsinvolved and upon the temperature. In general, the solubility'ofalkylatable hydrocarbons in hydrofluoric acid decreases with increase inthemolecular weight of the hydrocarbon and with approach in constitutionof the hydrocarbon to that of normal paramns. Experimentally, thesolubility of such hydrocarbons as isobutane, normal butane, benzene,and toluene in hydroiluoric acid has been found. to be in the rangeofabout 1.0 to 1.6 per cent by weight at 18 C., and it has been found toincrease with increase in temperature so that it is in the range ofabout 2.0 to 3.2 per cent at 16 C. and in the range of about 4.0 to 6.4per cent at 50 C. 0f these ranges, the lower values apply closely tonormal butane, and the upper values to benzene; intermediate valuesapply to isobutane and to toluene. These data show that the solubilityof typical alkylatable hydrocarbons in`hydrofluoric acid is doubled foran increase in temperature of about 34 C. Hence, the solubility of thesehydrocarbons is i-n the range of about 8 to 13 per cent at 84 C. and inthe range of about 16 to 26 per cent at 118 C. At some still highertemperature, complete miscibility is obtained. Similarly, the solubilityof hydroiluoric acid in the hydrocarbons increases with increase intemperature.

Because of the partial miscibility of hydrocarbons and hydroiluoricacid, it is advantageous, especially when an ,elevated alkylationtemperature is used, to cool the eilluent from alkylator i3, in order tofacilitate separation of it into an acid phase and a hydrocarbon phasein separator 2l. Although many forms of cooling may be used, aparticularly advantageous form consists of removing from the enluentalkylation mixture a low-boiling material comprising hydrofluoric acidin such a way that the residual material is cooled by direct evaporativecooling. Such cooling may be effected by passing the alkylation mixturefrom alkylator I3 through conduit 3l to cooler 32, wherefrom low-boilingmaterial comprising hydroiluoric acid is flashed oil as a vaporthrough-conduit 3l. The vaporization of this low-boiling materialremoves heat from the residual liquid mixture, which is then passedthrough conduit 35 to separator 2s.

Under some circumstances, the low-boiling material removed from cooler32 through conduit I3 may consist substantially entirely of hydroiluoricacid, as for example when no low-boiling hydrocarbon is present.Usually, however, a low-boiling hydrocarbon is present and is vaporizedin company with the hydroiluoric acid as a lowboiling areotropicmixture. When this hydrocarbon is an unreacted alkylatable hydrocarbon,and also when substantially only -hydrouoric acid is evaporativelyremoved from cooler 32, the lowboiling material from cooler 32 may beliquefied and recycled, as by pump 34 through line 31 and recycleconduit 3l, directly to alkylator Il When a low-boiling alkylatablehydrocarbon is through conduit 61 to recyclel conduit 38 `for re-A notremoved from cooler 32 in company with the vaporized lwdronuoric acid.as when-` the hydrocarbon being alkylated in alkylator I3 ls relativelyhigh-boiling, it is advantageous to add such a low-boiling hydrocarbonto the alkylation mixture, as through inlet 40. For example, when arelatively high-boiling hydrocarbon such as benzene or toluene is beingalkylated in alkylator' i3, a butane and/or a pentane may be so added.II'hen this added hydrocarbon is evaporatively removed from cooler `32as a low-boiling azeotropic mixture with hydroluoric acid throughconduit t3, and this azeotropic mixture is passed through conduit 42 toseparator 44. In separator 44 this mixture is separated, with the aid ofpreliminary indirect cooling if desired, into a hydroiluoric acid liquidphase and a hydrocarbon liquid phase. The hydrofiuoric acid phase isrecycled to alkylator I3, as through conduit 45 and through recycleconduit 38.

The hydrocarbon phase may be recycled to cooler 32, as through conduits48 and 4l. If, however, this hydrocarbon phase contains one or morehydrocarbons lower-boiling than the alkylatable hydrocarbon fed toalkylator I3 through inlet il, these lower-boiling hydrocarbonspreferably may be removed before it is recycled, and it is accordinglypassed through conduit 49 to separator 5I. From separator 5I, theselowerboiling hydrocarbons are removed, as by ilash or fractionaldistillation, and are withdrawn through outlet 52 and the residue isreturned to cooler 32, as through line 54 and conduit 55. Such removalof lower-boiling hydrocarbons has been found to be especiallyadvantageous in the hydrouoric acid alkylation of isopentane with olens,such as the butylenes and the amylenes, especially isobutylene, for insuch alkylation an extraordinarily high yield of concomitantly formedisobutane is formed, and this isobutane can be advantageously isolatedand used as an isoparaflinic alkylation feed to a different alkylationunit.

Although at times it is possible to carry the evaporative removal ofhydroiluoric acid from the alkylation mixture in cooler 32 to the pointof complete removal of this acid, such complete removal is usually notpracticed, so that ordinarily the mixture going to separator 29 containstwo liquid phases, namely, a hydrocarbon phase and a hydrofiuoric acidphase. In separator 29 thesev phases are separated, las by gravityand/or centrifugation. The acid phase may be passed through conduit 88to recycle conduit 3'8 for recycling to alkylator I3; but preferably atleast part of it is passed through conduit 90 to fractionating means 92for treatment as hereinafter described. The hydrocarbon phase is passedthrough conduit 6I) to separating means 62.

In separating means 62, which usually comprises a system offractional-distillation columns and auxiliary equipment, the hydrocarbonphase is separated into various fractions, which may be recycled orWithdrawn about as follows: Y.

(1) A relatively low-boiling fraction, if it consists of undesiredlow-boiling materials, may be withdrawn through outlet B3; or, if itconsists chiedy of the low-boiling parailin added through inlet 4I), itmay be passed through conduit Sito conduit 55 for recycling to cooler32; or, ir it is a low-boiling mixture of an unreacted alkylatablehydrocarbon, such as isobutane or isopentane, with hydrofluoric acid, itmay be passed cycling to alkylator Il.

(2) A major fraction, comprising chieily unreacted alkylatablehydrocarbon, maybe withdrawn, as through outlet 69, but it is preferablyrecycled to alkylator I3. as through conduit ll and recycle conduit 38.

(3) A major product fraction, of vdesired alkylate, is usually withdrawnthrough outlet 13. 1i' for any reason a trace, usually less than 0.01per cent, of organic nuorine in this fraction is objectionable, thisfraction may be passed through conduit 'I5 to purier "Il, wherein it iscontacted at a'suitable temperature, usually below about 200 C., with acontact mass 'capable of substantially removing' the undesired organicriuorine, such as for example bauxite, at a suit- 'able space velocity,such as for example 2 liquid volumes per volume per hour. The puriiiedalkylate then is withdrawn through outlet 18.

(4) A minor relatively high-boiling fraction comprising heavyby-products, such as polyal kylated hydrocarbons, which are especiallylikely to be formed when the initial alkylatable hydrocarbon isaromatic. may be withdrawn through outlet 8|); if desired, part or allof this fraction may be passed through conduit 82 to conduit `II forrecycling to alkylator I3, whereby the yield of monoalkylatedhydrocarbon is substantially enhanced; if desired, this fraction may beadvantageously treated in an auxiliary 'dealkylatoralkylator, not shown,with an excess of unalkylated hydrocarbon in the presence of hydrouoricacid under relatively drastic conditions, so as to convert it intomonoalkylated hydrocarbon.

In iractionating means 92, which usually consists of a system of one ormore fractional-distillation columns and auxiliary equipment, the acidphase coming to it from separator 29 is separated into variousfractions, which may be recycled or withdrawn about as follows:

(l) A major fraction comprising chieiiy anhydrous hydrofluoric acid,accompanied usually by a minor proportion of unreacted alkylatablehydrocarbon, is passed through conduit 83 to recyple conduit 33 forrecycling to alkylator I3.

(2) A smaller fraction comprising chiey unreacted alkylatablehydrocarbon is withdrawable through conduit S5.- but it is preferablypassed through conduit 91 to recycle conduit 38 for recycling toalkylator I3.

(3) At times, a minor fraction comprising a1- kylated hydrocarbons, asfor example alkylated aromatic hydrocarbons, is obtained and is passedthrough conduit 99 to separating means 62 for treatment as'alreadydescribed.

(4) At times, also, a minor fraction of polyalkylated hydrocarbons,obtained for example when the initial alkylatable hydrocarbon isaromatic, may be passed through conduit IUI to conduit 38 for recyclingto alkylator I3, or withdrawn through outlet |03. or it may be otherwisetreated similarly to the fraction available from separating 'means 62through outlet 80.

When the removal of hydrouoric acid from.

cooler l2 is practiced to the extent that only one liquid phase remains,the resulting residue may be passed directly to separating means 82, asthrough conduit 86; separator 23 and fractionating means 92 are thenunnecessary and are not used. As previously stated, this mode ofoperation is not usually practiced; for the primary purpose of cooler 32is that of cooling the' reaction mixture to facilitate separation intotwo phases, and not that of removing and/or purifying the acid. However,this mode of operation sometimes can be used to some advantage,especially when only a relatively small proportion of hydrofluoric acidis present in the mixture coming to cooler 32, as thereby the acid isrecovered in condition satisfactory for recycling to alkylator I3without the use of other recovery means, such as fractionating means 92.

In Fig. 2 is shown a vertical diagrammatic section of one form of mixeror agitator that may be advantageously used as alkylator i3 of Fig. l.It will be understood that Fig. 2 does not purport to show the mostdesirable dimensions and/or proportions, but that it has been drawn withcertain parts out of proportion in order to depict clearly certainadvantageous features. Hence, proportions departing widely from those ofFig. 2 may be used without passing beyond the scope of these particularaspects of the invention; similarly, parts made or arranged quitedifferently from those shown in Fig. 2 may be used, provided only thatthey perform substantially the same functions as those specically shownor described herein.

The reactor illustrated in Figs. 2 and 3 is a generally cylindricalshell 3 closed at one end by bottom 4 and at the other end by detachablecover 5, which may be attached to shell 3 by any suitable means, as by aflange-type joint with suitable clamps or bolts, not shown. Shell 3 isprovided with any desired number of inlets and outlets, exemplified byinlet I6 and outlet 21.

Cover has incorporated with it packing gland or stuffing box 22 aroundrotatable shaft 23. which is provided with one or more sets of stirrer,impeller, or propeller vanes or blades 6, designed or shaped so as notonly to agitate the-contents of shell 3 but also to cause internalrecirculation. Shaft 23 has an internal passageway l, which communicateson the one hand through space 8 with inlet I4 and on the other handthrough one or more orifices 25 with mixing and/or reaction zone 9 denedby shell 3, bottom 4, and cover 5; as previously discussed, thispassageway is advantageously used for the introduction of a reactant theconcentration of which is ldesired to be minimal in zone 9. Orifices 26may be constructed in any way that aids in the rapid dispersal ofmaterial passing through them into zone 9; usually they are preferablymuch smaller in diameter than passageway 1 and are further preferably ofa jet-like construction. They are preferably located at the points instirrer blades 6 at which maximal contact with the mixture in zone 9 perunit time is effected, but they may be located otherwise than asspecifically shown.

Leakage around shaft 23 below space 8 is prevented by packing IIJS,suitably graphited asbestos or the like, housed in the upper part ofgland 22. This packing may be compressed to anydesired extent bycompression member H0, which cooperates with gland 22 through atightening means exemplified by rotatable annular ring lll cooperatingwith gland 22 as by threads H2. As already discussed, this packing isadvantageously protected from the mixture in zone 9 by the sweepinpassage of material relatively inert to the packing, such as analkylatable hydrocarbon, from inlet Il through annular space III betweenshaft 23 and apron 25 into zone i. Leakage around shaft 23 above space 8is similarly prevented by packing IH, housed in the upper end ofcompression member H0, which at this point is similar in function to theupper part of gland 22. This packing may be tightened or compressed toany desired extent by tightening member l l5, which cooperates with theupper part of member H0, as through screw threads IIB, in a manner wellunderstood in the art. It will be understood that the arrangement shownin Figure 2 is schematic and that various known modifications, such asfor example the use of lantern glands and of forced lubrication of shaft23 at points in contact with packings |09 and H4, may be practicedwhenever advantageous or convenient.

Cooperating in the mixing function of rotating vanes or blades 6 may beone or more sets of stationary vanes H1, angularly spaced andcorresponding in number and vertical spacing to blades 6, supported asfrom cover 5 by supporting members H8 which are shown as rod-like inform but which may be an annular member. One of members IIB is shown asbeing provided with passageway H9 for introduction of one or morereactants, or of the catalyst, from inlet |20 through orifices or jets|2l in vanes I I1 into zone 9, in the manner already indicated. Theorifices I2! may desirably be substantially smaller in diameter thanpassageway H8, similarly to orifices 26 in vanes 6. Certain princi-plesalready discussed apply to such introduction; for example. if part orall of an olefin or other alkylant is introduced into zone 9 throughorifices |2I, the catalyst should be introduced through some otherinlet, such as inlet I6.

As an example of the alkylation of a relatively readily alkylatablehydrocarbon may be taken the alkylation of benzene with oleiins in thepresence of concentrated or anhydrous hydrofluoric acid in a continuoussystem of the type described herein and illustrated in Fig. l. Thehydroiiuoric acid is introduced, as through inlet I6, into alkylator i3,which is preferably provided with a single or multiple agitating unit ofthe turbo-mixer type; after a steady state of operation is reached, onlymake-up acid to replace lost acid and acid withdrawn from the system isadded through inlet I6.

Benzene is added, as through inlet H, to the alkylator in a mannerdesigned to protect the packing around the rotating shaft of theturbomixer unit, passing from this packing toward the interior of thealkylator as within apron 25. Most of the benzene going to thealkylator, however, is passed in admixture with the alkylating olenthrough the shaft of the agitating unit and into the reaction zonethrough jet-type openings at points in the unit having relatively highlinear velocities, as at the extremities of the blades of this unit.Thereby an extraordinarily rapid dispersal and mixing of the incomingfeed with the already present and internally recirculating mixture ofhydrocarbons and hydroiluoric acid is obtained, with a resultantextraordinarily high alkylation emciency, so that the consumption ofolefin by reactions other than alkylation is negligible or virtuallynil.

The temperature at which the alkylation is performed depends somewhatupon the particular olefin being used to alkylate the benzene. For

alkylation made with an average Itime of residence of the hydrocarbonsin the reaction zone of about v to 50 minutes, Iand with a ratio ofhydrocarbons to acid of about 1 by volume, it is preferably in thefollowing ranges for ethylene, for propylene, and for butylene,respectively: 100 to 200 C., 50 to 100 C., and 0` to 50 C. When `thereaction temperature is above about 40 C., the reaction mixture eiiluentfrom the reaction zone is preferably cooled, as :by reducing thepressure and allowing some hydrofluoric acid to be flashed ofi',preferably after addition of a quantity of butane at least suicient toform a low-boiling azeotropic mixture with the hydrofluoric acid that isflashed oi. The cooled mixture is then separated into an acid phase anda hydrocarbon phase ina settler. and the tWo phases are furtherprocessed and fractionated substantially as has been described.

The yield of alkylate is relatively high, usually being above 90 percent of the theoretical yield of monoalkylbenzene and at timesapproaching much closer to 100 per cent. For example, in the continuousisopropylation of benzene .by hydrofl'uoric Iacid at 50 C. for a contacttime of 60 minutes, in which the mol ratio of benzene to olefin in thefeed was 8.3, the yield of alkylate was about 90 per cent by weight ofthe theoretical yield oi monoisopropyl'benzene, and the alkyl-atecontained almost 95 per cent of monoisopropylbenzene. the rest of thealkylate being chiey diisopropylbenzene. ln alkylation of benzene withisobutylene at substantially the same conditions except that the molratio of benzene to olefin in the feed was 5.07, the yield of alkylatewas 91.8 per cent by Weight of the theoretical yield ofmonobutylbenzene, and the alkylate contained 92.0 per centmono-tertiary-butylbenzene, 7 .5 per cent di-tertiary-butyl'benzene, andonly 0.5 lper cent of higher-boiling material. In a similar alkylationof benzene with ethylene at 117 C. for a contact time of 54 minutes, theyield of alkylate was only slightly below 90 per cent of the.theoretical yield oi monoethylbenzene, and the alkylate contained 85per cent of monoethylbenzene, the rest being mostly diethylbenzene. Themonoethylbenzene was highly suitable for the formation of styrene bydehydrogenation, as by the catalytic action of catalysts comprisingchromium oxide.

Similar procedures serve for the hydroiiuoric acid alkylation ofisoparalns, such as isobutane, isopentane, and/or isohexane, witholefins such as propylene, butylenes, and/or amylenes. The conditionsmay vary widely, lbut for optimum results with a ratio of hydrocarbonsto acid of about 1 and with a contact time of about 5 to 30 'minutes,the temperature preferably may be in the range of to 40 C., which is arange readily obtained by removing the exothermal heat of reaction bythe evaporative cooling described hereinlbefore, applied, if desired,directly to the alkylatlon zone. In such cooling, the addition of alow-boiling hydrocarbon to form an azeotropic mixture with thehydrouoric acid is not necessary, because of the presence of unreactedlsoparaflin and further because in the hydrofluoric acid alkylation ofisoparains heavier than isobutane there is concomitantly formed anunexpectedly large proportion of isobutane, which serves as a suitablelow--boiling hydrocarbon. For example, in the hydrofluoric acidalkylation of isopentane with isobutylene at a temperature of 18 to 30C. and an average contact time of 20 minutes, the concomitantly :formedisob'utane amounted to 261 per cent :by weight of the isobutylene, andin a similar alkylation at 3 to 16 C. it amounted t0 200 per cent. In alikewise similar alkylation of isopentane with amylenes at 23 to 38 C.,the concomitantly formed isobutane amounted to 165 per cent by weight ofthe original amylenes. In such alkylation of isopentane, unexpectedlyand exceedingly high yields of total depentanized product are obtained;in the three alkylations just mentioned, these yields were n35, 443, and437 per cent lby weight of the original olen,or 234, 194, and 216 percent of the theoretical yield of alkylate computed on the basis of onemolecule of olen reacting with one molecule of isopentane. Theconcomitantly formed isobutane is preferably removed as hereinbeforedescribed, as through outlet 52, instead of being recycled withunreacted isopentane to the alkylation. zone, for the over-all yield ofdepentanized Ialkylate is thereby somewhat increased, perhaps lbecauseconsumption of olen Iby concurrent alkylation of isobutane is therebyminimized.

Because the invention may loe practiced otherwise than yasspeciiicallyshown herein, and because many variations and modiiicationsof it will be obvious to those skilled in the art, the invention shouldnot be restricted except as specifically indicated in the appendedclaims.

I claim:

l. A process for the catalytic alkylation ofv an alkylatable hydrocarbonwith an alkylating agent in the presence of a liquid alkylation catalystwhich comprises introducing the alkylatable hydrocarbon and the liquidalkylation catalyst into a reaction zone, maintaining a relatively largebody of liquid reaction mixture under alkylating lconditions in saidzone, agitating said body of reaction mixture, introducing thealkylating agent into said :body of reaction mixture through an orifice.and throughout said introduction moving said orifice at high speedthrough the body of reaction mixture in said zone and thereby effectingrapid dispersal of said alkylating agent throughout said body ofreaction mixture, [preventing local yconcentrations of the alkylatingagent in said body and maintaining the concentration of the alkylatingagent throughout the reaction zone at the desired minimum.

2. A process for the catalytic alkylationl of an alkylata-blehydrocarbon with an alkylating agent in the presence of a liquidalkylation catalyst consisting essentially of substantially anhydroushydroiiuoric acid which comprises introducing the alkylatablehydrocarbon and the liquid alkylation catalyst into a reaction zone,maintainlng a relatively large body of liquidreaction mixture underalkylating conditions in said zone, agitating said body of reactionmixture, introducing the alkylating agent into said body of reactionmixture through an orice, and throughout said introduction moving saidorifice at high speed through the body of reaction mixture in said zoneand thereby effecting rapid dispersal of said alkylating `agentthroughout; said lbody of reaction mixture, preventing localconcentrations of the alkylating agent in said body and maintaining theconcentration of the alkylating agent throughout the reaction zone atthe desired minimum. l

MARYAN P. MATUSZAK.

